Impact of Fire Suit Ensembles on Firefighter PAH Exposures

By Oxford University Press

Some 10 years ago, on a work-force initiative, firefighters in Sweden started to introduce a number of safety measures aimed at reducing exposure to combustion particles in their occupational environment (Magnusson and Hultman, 2014). A majority of the routines were focused on reducing secondary exposure by avoiding handling of used equipment and minimizing the time firefighters wore contaminated suits and base layers after fire operations. These routines were implemented by, for example, keeping used materials in separate compartments in the truck as well as changing into clean clothes before returning to the fire station.

At present, newly built fire stations are designed containing zones divided according to their suspected degree of contamination, all to reduce secondary exposure while preparing for future assignments or turn-outs. Encouragingly, a majority of firefighters in Sweden adopted the routines in full, driven by an awareness that such actions reduce their risk of developing cancer. Gas and particles containing carcinogenic compounds, such as several polycyclic aromatic hydrocarbons (PAHs), have been recognized as an adverse risk for a number of occupations including asphalt workers, aluminium workers, chimney sweepers, and coal power plant workers (Boffetta et al., 1997). Several of these PAHs, of which a majority are associated with airborne particles, have been assigned a toxic equivalency factor (TEF, Delistraty, 1997) or been classified by the International Agency for Research on Cancer (IARC) as either carcinogenic (Group 1), possibly carcinogenic (2A) or probably carcinogenic (2B) to humans. Quite recently, IARC also specifically evaluated firefighters’ occupational exposure to be on the level “possibly carcinogenic to humans” (Group 2B) (IARC, 2010). These evaluations are not trivial since exposure dimensions are particularly difficult to assess for a workgroup involved in multiple work tasks, often part-time (e.g. volunteer firefighters), and intermittently exposed to high levels of an extremely complex composition of gases and particles produced from combustion. Note that PAHs are not the only candidates in smoke from fires that can potentially cause cancer (IARC, 2010; Tsai et al., 2015). In addition, exposure may occur through both skin and lungs (Fent et al., 2014) and at various phases and microenvironments during a turn-out (Baxter et al., 2014), making exposure assessment a challenging task. Although being an indirect indicator of all PAHs (Jongeneelen, 2001), biomonitoring of levels of the metabolite 1-hydroxypyrene in urine has commonly been the preferred choice when assessing multi-route PAH exposure for the above-mentioned groups. For several reasons, conclusive proof of its suitability for assessing firemen’s exposure has so far not been demonstrated (Caux et al., 2002; Robinson et al., 2008; Laitinen et al., 2010; Fernando et al., 2016; Oliveira et al., 2016). Possibly, the optimal metabolite to represent the levels of particle-associated carcinogenic PAHs, or those being assigned TEF-values, is 3-hydroxybenzo[a]pyrene, but its levels in urine are generally very low, since the largest proportion is excreted in faeces.

Alternative methods and suggestions for measuring firefighters’ exposure may include monitoring of the lighter two-ring and three-ring mono-hydroxylated PAHs (Oliveira et al., 2016) and methoxyphenols in urine (Fernando et al., 2016), analysing skin wipes (Fent et al., 2014) or by the use of biomarkers in breath samples (Pleil et al., 2014). The newly adopted safety measures also involved protecting airways from inhalation exposure at all times—parking vehicles upwind and by methodical use of respirators (i.e. self-contained breathing apparatus [SCBA] or full-face filter masks) whenever smoke can be smelled. If exposure due to inhalation can be kept low, dermal uptake after passage through the fire ensemble and the base layer remains the vulnerable area that needs further investigation.

The objectives of this study were to investigate work protection factors (WPFs) for PAHs in realistic conditions with the combination of a fire jacket and base layer during an active smoke diving exercise (exercise 1), and to assess exposure by measuring skin deposition of PAHs and levels of PAH metabolites in urine during a standardized smoke diving exercise (exercise 2). The latter exercise is part of the examination at the two colleges of the Swedish Civil Contingencies Agency for prospective firefighters in Sweden, with a similar version being used as a regular yearly follow-up exercise for firefighters on active service.

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